The previous work by this group has established a direct correlation between rhythmic alternations of cerebral hemispheric activity and altering cycles of autonomic function. The nasal cycle is an ultradian rhythm with 75-200 min. periodicity in which airflow through the nares predominates unilaterally. This activity is presumed to be regulated via peripheral vasomotor activity with unilateral sympathetic dominance in one nostril coordinated with parasympathetic dominance in the other. The nasal cycle was found to correlate in phase with a shift in hemispheric dominance in 22 subjects. Dominance of right nostril airflow is associated with relatively greater integrated EEG amplitude in the left hemisphere and vice versa (p less than 10 to the minus 6th power). Having established this correlation of the nasal cycle with alternating cerebral dominance during wake, we decided to determine if this relationship existed during sleep. There is strong evidence to suggest that an ultradian rhythm of alternating cerebral dominance, measured by EEG, correlates with the REM-NREM sleep cycle (Goldstein, 1972). REM sleep is associated with relatively greater left hemisphere EEG amplitude and NREM sleep with relatively right hemisphere EEG amplitude. The objective is to demonstrate a correlation of these ultradian rhythms during sleep as follows. Dominant right nostril airflow is associated with REM sleep and relatively greater left hemisphere EEG amplitude. Conversely, dominant left nostril airflow is associated with NREM sleep and relatively greater right hemisphere EEG amplitude. We intend to demonstrate that these cycles are correlated to one another and are actually a representation of the same phenomena. This relationship will be demonstrated by recording from a number of cortical areas. Subjects will be requested to sleep in the laboratory under conditions which are as similar as possible to their normal nights sleep. The EEG, eye movements and muscle tone are recorded by standard procedures. Thermistors are used to measure nasal airflow throughout the night. The EEG and airflow recordings are subjected to continuous integration which are exhibited on the polygraph. The sleep stages are determined by standard methods and indicated on the integration tracings as REM-NREM periods.